A new technique for hiding data in emails via Outlook Express and IE is proposed. Secret data are encoded by special ASCII control codes and embedded into cover emails by inserting the data into email text line ends.
These special codes were found by systematically testing all the ASCII codes of various email server software systems and standards. The codes are invisible to the user when displayed, achieving the effect of steganography.
The proposed data encoding technique is a combination of five coding rules. The inserted codes do not change the meaning of the sentences in the cover email, neither cause any noticeable difference to the reader.
Furthermore, hidden data can be completely extracted from a tego-email to recover the original email text. Also, two applications of the proposed data hiding technique, namely covert communication via emails and authentication of emails, are described. In the first application, security is enhanced by the use of a secret key, and in the second, an authentication signal is generated from the cover email for email fidelity checking. Good experimental results show the feasibility of the proposed method.
Proceedings of 2007 National Computer Symposium, Taichung, Taiwan, Republic of China